Supplementary appendix
---for the article titled 'Intra-operative open-lung ventilatory strategy reduces postoperative complications after laparoscopic colorectal cancer resection: A randomized controlled trial'
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1. Pre-operative risk index for postoperative pulmonary complications...2
2. The procedures of lung recruitment maneuver (LRM)...3
3. Predicted body weight (PBW)... 3
4. Ventilators and monitors... 3
5. Definitions for pulmonary complications... 4
6. Definitions for intra-operative ventilation strategy related complications...5
7. Definitions for postoperative extrapulmonary complications...6
References... 7
1. Pre-operative risk index for postoperative pulmonary complications
Pre-operative risk factor1,2 Point Value
Type of surgery
Abdominal aortic aneurysm repair 15
Upper abdominal 10
Age
≥ 80 years 17
70–79 years 13
60–69 years 9
50–59 years 4
Functional status
Totally dependent 10
Partially dependent 6
Weight loss > 10% in past 6 months 7
History of chronic obstructive pulmonary disease 5
General anesthesia 4
Impaired sensorium 4
History of cerebrovascular accident 4
Blood urea nitrogen level
< 2.86 mmol l-1 4
7.85–10.7 mmol l-1 2
≥ 10.7 mmol l-1 3
Estimated intra-operative blood transfusion amount > 4 units 3
Emergency surgery 3
Steroid use for chronic condition 3
Current smoker within 1 year 3
Alcohol intake > 2 drinks day-1 in past 2 weeks 2
Risk Class Risk Class 1 Risk Class 2 Risk Class 3 Risk Class 4 Risk Class 5 0–15 points 16–25 points 26–40 points 41–55 points > 55 points
2. The procedures of lung recruitment manoeuver (LRM)
A stepwise increment of the tidal volume was used for each LRM, as previously described.3-5 We set PEEP at 12 cmH2O and respiratory rate at 6 breaths min-1, then increased tidal volume in steps of 4 ml kg-1 of PBW until the plateau pressure reached 30–35 cmH2O and hold mechanical ventilation settings for 3 breaths. Then, we set respiratory rate, PEEP, and tidal volume back to the values preceding the LRM. A LRM should not be performed if mean arterial pressure (MAP) is ≤ 65 mmHg or heart rate is ≤ 45 beats min-1, and RM should be stopped if MAP reaches ≤ 55 mmHg or heart rate reaches ≤ 45 beats min-1.
3. Predicted body weight (PBW)
PBW was calculated according to a predefined formula6 with: 50 + 0.91 * (centimeters of height – 152.4) for males and 45.5 + 0.91 * (centimeters of height – 152.4) for females.
4. Ventilators and monitors
In each group, patients were ventilated using the volume-controlled ventilation strategy using an anesthesia ventilator: (1) Avance® (Datex-Ohmeda, General Electric, Helsinki, Finland);
(2) Fabius Tiro® (Dräger, Lübbeck, Germany). Patients were monitored using an monitor:
Datex Ohmeda S/5® (GE Healthcare Finland Oy, Helsinki, Finland).
5. Definitions for pulmonary complications
Major postoperative pulmonary complications were defined as acute respiratory failure, suspected pneumonia and sustained hypoxaemia.
(1) Suspected pneumonia: 1,5,7-9
Patient receives prophylactic antibiotics and meets at least one of the following criteria:
(i) the presence of new and/or progressive pulmonary infiltrates on chest X-ray plus two or more of the following: (a) fever ≥ 38.5°C (core temperature); (b) leukocytosis with white blood cell (WBC) count of ≥ 12 ×109l-1 or neutrophil > 80%; (c) purulent sputum; (d) new onset or worsening cough or dyspnea.
(ii) without chest X-ray and in the absence of other infectious focus (i.e., urinary or biliary tract infection, intestinal obstruction, intra-abdominal abscess or anastomotic leakage), and the presence of three or more of the following criteria: (a) fever ≥ 38.5°C (core temperature);
(b) leukocytosis with WBC count of ≥ 12×109l-1 or neutrophil > 80%; (c) purulent sputum;
(d) new onset or worsening cough or dyspnoea.
(2) Acute respiratory failure: 7-9 PaO2 < 60 mmHg or SpO2 < 90% in room air lasting more than one minute at follow-up when awake.
(3) Sustained hypoxaemia: SpO2 ≤ 92% in room air lasting more than one minute at follow- up when awake for more than consecutive three days.
Definitions in post hoc analysis of pulmonary complications
(4) Modified acute respiratory failure: met the criterion of acute respiratory failure in twice follow-up or acute respiratory failure with sustained hypoxaemia.
(5) Severe respiratory failure: Experienced an invasive or noninvasive ventilator therapy, or PaO2 < 60 mmHg or SpO2 < 90% when administering oxygen via a nasal catheter at 3 l min-1 or more.
6. Definitions for intra-operative ventilation strategy related complications
Pneumothorax: defined as the presence of air in the pleural space with no vascular bed surrounding the visceral pleura,8 diagnosed during the operation and within 3 days after surgery.
Potentially harmful hypotension: Mean arterial pressure (MAP) ≤ 55 mmHg lasting longer than 1 minute.
Need for vasopressors: Mean arterial pressure (MAP) ≤ 55 mmHg or the need for a vasopressor, as assessed by an anesthesiologist, when MAP < 65 mmHg.
7. Definitions for postoperative extrapulmonary complications
Major extrapulmonary complication includes sepsis, severe sepsis, septic shock and death within 7 postoperative days. All complications are assessed based on previously defined criteria. 10
(1) Systemic inflammatory response syndrome (SIRS) is defined as those who meet the following two or more criteria: (i) Core temperature > 38°C or < 36°C. (Core temperature is rectal or tympanic). If oral, inguinal or axillary temperatures are used, add 0.5°C to the measured value. (ii) Heart rate > 90 beats min-1. If patient had an atrial arrhythmia, record the ventricular rate. If patients have a known medical condition or are receiving treatment that would prevent tachycardia (for example, heart block or beta blockers), they must meet two of the remaining three SIRS criteria. The most deranged value recorded must be used. (iii) Respiratory rate > 20 breaths min-1 or a PaCO2 < 32 mmHg or mechanical ventilation for an acute process. (iv) WBC count of > 12 ×109l-1 or < 4 ×109l-1 or neutrophil > 80%.
(2) Sepsis is defined as (i) A clear site of infection and at least compliance with the SIRS diagnosis; (ii) The specific site of infection refers to the presence of microbial growth in the blood or other sterile areas, or the formation of abscesses, or the presence of tissue or organ infections (e.g., pneumonia, peritonitis, urinary tract infection, endovascular infection, soft tissue infection, etc.).
(3) Severe sepsis is defined by sepsis plus at least one organ failure, hypotension or hypoperfusion.
(4) Septic shock is sepsis-induced hypotension despite adequate fluid resuscitation along with the presence of perfusion abnormalities.
(5) Acute myocardial infarction is defined11as a rise of Troponin with at least one of the following: (i) Symptom of ischaemia; (ii) electrocardiogram changes indicating new ischaemia (new ST-T changes or new left bundle branch block); (iii) development of pathological Q waves in the electrocardiogram.
(6) Modified postoperative hospital stay: On the basis of the primary outcome analysis population, this analysis excluded the patients who had none of the primary outcome events but had a postoperative hospital stay more than 10 days.
References
1. Futier E, Constantin JM, Paugam-Burtz C, et al. A trial of intraoperative low-tidal-volume ventilation in abdominal surgery. N Engl J Med 2013; 369: 428-37.
2. Arozullah AM, Khuri SF, Henderson WG, et al. Development and validation of a multifactorial risk index for predicting postoperative pneumonia after major noncardiac surgery. Ann Intern Med 2001; 135: 847-57.
3. Severgnini P, Selmo G, Lanza C, et al. Protective mechanical ventilation during general anesthesia for open abdominal surgery improves postoperative pulmonary function.
Anesthesiology 2013; 118: 1307-21.
4. Hemmes SN, Gama de Abreu M, Pelosi P, et al. High versus low positive end-expiratory pressure during general anaesthesia for open abdominal surgery (PROVHILO trial): a multicentre randomised controlled trial. Lancet 2014; 384: 495-503.
5. Hemmes SN, Severgnini P, Jaber S, et al. Rationale and study design of PROVHILO - a worldwide multicenter randomized controlled trial on protective ventilation during general anesthesia for open abdominal surgery. Trials 2011; 12: 111.
6. Acute Respiratory Distress Syndrome N, Brower RG, Matthay MA, et al. Ventilation with lower tidal volumes as compared with traditional tidal volumes for acute lung injury and the acute respiratory distress syndrome. N Engl J Med 2000; 342: 1301-8.
7. Gallart L, Canet J. Post-operative pulmonary complications: Understanding definitions and risk assessment. Best Pract Res Clin Anaesthesiol 2015; 29: 315-30.
8. O'Gara B, Talmor D. Perioperative lung protective ventilation. BMJ 2018; 362: k3030.
9. Jammer I, Wickboldt N, Sander M, et al. Standards for definitions and use of outcome measures for clinical effectiveness research in perioperative medicine: European Perioperative Clinical Outcome (EPCO) definitions: a statement from the ESA-ESICM joint taskforce on perioperative outcome measures. Eur J Anaesthesiol 2015; 32: 88-105.
10. Cohen IL. Definitions for sepsis and organ failure. The ACCP/SCCM Consensus Conference Committee Report. Chest 1993; 103: 656.
11. Thygesen K, Alpert JS, White HD, et al. Universal definition of myocardial infarction.
Circulation 2007; 116: 2634-53.
